Genioglossus and Intrinsic Electromyographic Activities in Impeded and Unimpeded Protrusion Tasks

This study focuses on the muscular actions leading to tongue protrusion under conditions where protrusion is either impeded or unimpeded

Lora J. Pittman

2008

Scholarcy highlights

  • Our understanding of the principles governing the nervous system control of movement in large part comes from studies conducted in muscles of the limbs that have clearly defined origins and insertions and that produce force across a joint
  • For the unimpeded protrusion task, subjects were instructed to maintain the tongue in the least-protruded position that was associated with stable motor-unit discharge for 10 s
  • The absence of any correspondence between firing rate and force during impeded protrusion tasks supports the hypothesis that GG motor-unit activities are modulated in accordance with tongue position, but not isometric force production
  • Hydrostats have been extensively studied at a kinematic level yet we know remarkably little about patterns of muscle and motoneuron activities and their relationship to hydrostatic movements
  • We show that whereas there is activation of GG and intrinsic tongue muscles in both tasks, the magnitude and shape of the drive to the intrinsic muscles and to the GG are very different, at least within the framework of the simple tasks attempted here
  • It is our view that the force targets were within the physiological range and that the EMG activities reported here in impeded protrusion tasks approximate those developed by the tongue in speech and some gustatory functions
  • We suggest that GG activation plays a central role in impeded protrusions, providing a stable platform against which the intrinsic muscles in the anterior tongue can develop protrusive force against immobile structures such as the teeth or palate

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